Ext.ComponentQuery.query() only creates an empty array

Ext.ComponentQuery.query() only creates an empty array

I'm just migrating a large Application from ExtJs 3 to ExtJs 4 and I'm annoyed by one problem.

The application consists of a lot of classes named according to an MVC approach. For example (MyApp.Domain.View.PersonView).
If I try to refer to an Object which I can easily find by stepping up in the object-hierarchy from one ownerCt to the next one with Ext.ComponentQuery.query(<itemId of the searched Object>) I always get an empty Array back.